Highly Accelerated Life Testing (HALT) is a qualitative test method used to accelerate and identify failures in products, such as medical devices. The products are tested to failure to find failure modes and to identify the root causes of product and sub-system failures. Once failure modes and causes are identified, the product design can be improved to prevent or reduce the identified failures. The improved product design can then be retested to confirm that the identified failures are reduced. The HALT process results in rugged designs and high reliability products.
The HALT process can apply any stimulus to a product under test that can accelerate failure in the product, providing an indication of failures likely to occur in the field. One stimulus is temperature stress, which can be used in electronics testing to identify failures due to marginal components, poor timing margins, and poorly mounted heat sinks. Another stimulus is vibration, which can be used in mechanical and electronics testing to identify failures due to poor solder joints, loose hardware, and contact and wear between adjacent parts. Other stimuli used to accelerate failure can include general humidity, over-voltage, and over-current.
Unfortunately, present HALT processes are not able to provide a stimulus which accelerates oxidation in the product under test. Oxidation in the field normally occurs over a number of years, so failures in products in the field are too late to contribute to improved product design. The inability to accelerate oxidation during HALT processes prevents product design improvements from determining how oxidation affects the function of the device and identifying areas on which to focus design efforts. This, in turn, prevents achievement of highest product quality, product reliability, and patient safety.
It would be desirable to have an accelerated life testing device and method that would overcome the above disadvantages.